"The biggest mobile developer study in history with 6,000 respondents from 115 countries says that while iOS developers make an average of $5,200 per month in app revenue and Android developers pull in $4,700, more developers plan to start developing for Windows Phone than any other platform. [...] That's aided, of course, by the fact that 71 percent of mobile developers are already developing for Android, and 56 percent are already developing for iOS." I'm surprised there's so little difference between income for iOS and Android developers. Reading the web, it often seems as if all iOS developers are millionaires and Android developers are poor unwashed peasants. Reality is, clearly, different.

To me, ad-supported apps are a curse. I gladly pay a dollar to have an app without apps. Heck I'd pay 2 or 3 or in some cases up to 5 if the app is good enough just to get rid of ads. Unfortunately on Android sometimes that isn't even an option. For example: The official Scrabble app exists as a free with ads and a paid version without ads on iOS. On android it's only the free version, which is so crammed with ads it's completely unplayable.

No. The data says iOS is still a lot more profitable. I don't see how this survey fits in to the actual data, but then again it is just self-reports which aren't very reliable.

Top iOS apps earn 4.6x more than Android, but Google Play is gaining ground.....

A possible explaination could be that an iOS app per installed device device is 4.6x more profitable than the equivalent Android device. As there are much more Android devices in the nature, the overall earn per released app is much closer.